<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8" />
		<title></title>
		<script type="text/javascript">
			window.onload=function(){
				var mybtn=document.getElementById("btn");
				mybtn.onclick=function(){
					//避免死循环:条件不要永远为真
					for(var i=1; i<=15; i+=3){
						console.log(i);
					}
				}
			}
		</script>
	</head>
	<body>
		<input type="button" value="点我" id="btn" />
	</body>
</html>
